1. Field of the Invention
The present invention relates to a method for manufacturing semiconductor devices and, more particularly, to a method for manufacturing a wiring board having a bonding pad for flip chip bonding and a bonding pad for wire bonding, and to a semiconductor device using a wiring board obtained by the manufacturing method.
2. Description of the Related Art
In the related art, there is a method of mounting a semiconductor element 10 by flip chip bonding, and a semiconductor element 12 by wire bonding, on a single substrate 14 (Refer to U.S. Pat. No. 6,781,221). FIG. 6 shows an example of a semiconductor device produced by employing a method of mounting two semiconductor elements 10 and 12 on the substrate 14 by stacking the elements and of sealing the semiconductor elements 10 and 12 with resin 19. To mount the semiconductor elements 10 and 12 by stacking thereon, in the semiconductor device, the lower semiconductor element 10 is mounted on the substrate 14 by flip chip bonding, while the upper semiconductor element 12 is mounted thereon by wire bonding. Reference numeral 20 designates a bonding bump formed on an electrode of the semiconductor element 10. Reference numeral 16 denotes a bonding pad for flip chip bonding. Reference numeral 18 represents a bonding pad for wire bonding. Reference numeral 22 denotes a bonding wire.
The method of mounting the semiconductor elements on the substrate 14 by utilizing flip chip bonding and wire bonding is effective in miniaturizing the semiconductor device. However, the semiconductor elements are mounted thereon by different connection configurations, that is, flip chip bonding and wire bonding. Thus, bonding pads 16 for flip chip bonding, and bonding pads 18 for wire bonding should be formed on the substrate 14.
FIG. 7 illustrates a state in which the bonding pad 16 for flip chip bonding and the bonding pad 18 for wire bonding are formed on the substrate 14. According to the mounting configuration of the semiconductor elements 10 and 12, the bonding pads 16 for flip chip bonding are placed along the inner side of the bonding pads 18 for wire bonding.
Meanwhile, bumps 20 (gold bumps) formed on the semiconductor element 10 are respectively bonded to the bonding pads 16 for flip chip bonding. Bonding wires (gold wires) are connected to the bonding pads 18, respectively. Thus, different surface treatments are performed on the pads 16 and 18.
That is, solder is applied to the surface of the bonding pad 16 in such a way as to cover the pad 16, while plating for bonding (for example, nickel plating and gold plating) is applied to the bonding pad 18. Thus, a related-art method is performed so that after a wiring pattern and the pads to be used as the bonding pads 16 and the bonding pads 18 are formed, first, plating is applied to the pads to be used as the bonding pads 18, and that subsequently, solder is applied to the pads to be used as the bonding pads 16, in such a way as to cover the pads 16.
When plating is applied to the pads to be used as the bonding pads 18, parts to be used as the bonding pads 16 are masked by a plating device, so that plating is applied only to the bonding pads 18. When solder is applied to the pads to be used as the bonding pads 16 in such a way as to cover the pads 16, the solder is applied to the bonding pads 16 by shielding the bonding pads 18 in such a way as to prevent the solder from applying to the bonding pads 18.
In a case where the bonding pads 16 for flip chip bonding are formed at extremely fine intervals, the following method is employed. That is, when solder is applied to the pads in such a way as to cover the pads, an adhesive layer is formed on each of the pads, and then solder powder is made to adhere to the pads with adhesive layer. Subsequently, the solder powder is melted to thereby apply the solder onto the surface of each of the pads in such a way as to cover the pads. In a case where solder is applied to the pads in such a manner as to cover each of the pads by performing this method, it is necessary to prevent the solder powder from adhering to unnecessary parts, such as the bonding pads 18. A practical mass production line requires a manufacturing method with good-workability, which is enabled to surely cover the surfaces of the bonding pads 18 and to surely cause solder to adhere only to the bonding pads 16.